mm/vmstat: add NRSWP{IN,OUT} counters

Count how many swap I/Os we cause.  Due to batching this can be different
than the current counter number of pages written/read, and tracking this
information is useful to see how efficient the batching is.

The counters are added at the end of enum vm_event_item and the
vmstat_text array under the assumption that the order of fields in
/proc/vmstat is an ABI.  If that is not the case, they could be grouped
with the other swap counters.

Link: https://lore.kernel.org/20260713093350.2154226-8-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Youngjun Park <youngjun.park@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

0 files changed, 0 insertions, 0 deletions